A drone that finds survivors through their phones

July 16, 2014

A drone makes large circles in the sky. With two powerful antennas, it sniffs the data packets emitted by mobile phones. On the ground, an interface developed specifically for this project makes it possible to track the flight of a small robotic aircraft in real time from a computer. Colored dots visible on the screen map indicate the spotted phones. The vehicle tightens its flight around the selected device to indicate its position. "In the best tests we have performed, the place indicated was within 10 meters," says Jonathan Cheseaux who worked on this project for his master's degree.

Following an earthquake or another natural disaster, it is often difficult to know the position of victims under the rubble. At a time when most people, even in poor countries, have a mobile phone, the team of Mobile Communications Laboratory had the idea of using them to know the position of victims and thereby facilitate a search. When WiFi mode is activated, the devices emit data packets at regular intervals so that it's possible to know various parameters, including the power received by the antenna connection. This can vary depending on the surrounding terrain, the weather or interference. It is also weaker as the layer of rubble over a person is thicker—another important factor.

But there is little similarity between these signals and a distance in meters that would make it possible to know directly the position of the device. With the drone, it is the GPS points of the captured signals from several places that locate the phone. These benchmarks are considered the center of circles which could potentially find the phone. The intersection of the latter determines the location of the phone and, therefore, probably the person. "By refining the system to automatically eliminate weaker signals, the system has become even more accurate," explains the master's student. "Flight tests have located a cell phone on campus with high accuracy."

"The drone's WiFi antenna could be replaced by Avalanche Victim Detectors (DVA) which would enable the rapid and inexpensive deployment of the first avalanche searches," predicts the student, who is also an amateur mountaineer.

In the second part of his work, Jonathan Cheseaux also noted the challenge of connecting to the WiFi network of a device through the drone – without human intervention. An antenna on the plane permits the device to guess the identity of the router that connects the phone and then pretends to be it. It can thereby establish communication. "In the case of natural disasters mentioned above, it would provide a substitution network when connections have been destroyed," he says. But for now, this system only works if the network is open and not password protected. This work has also helped highlight issues of confidentiality and the protection of private data. Recovering the names of registered WiFi (SSID) by a smartphone is done to establish the habits of owners. For example, it may have a list of "EPFL," "Fitness," "Café-so," "House," et cetera. The MAC address, a unique identifier, can also be recovered by the drones. It identifies the device brand and deconstructs statistics on the distribution of smartphone / router / printer brands.

Related Stories

Cell phones are getting ever smarter today, savvy enough to tell you where to go and what to buy in shopping centers or department stores. Although still in nascent stages, indoor positioning and navigation using mobile phones ...

(Phys.org) —Well known hacker Samy Kamkar has figured out a way to program a store-bought drone to take away control of other store-bought drones from their owners, and then to give the enslaved drones commands of its own. ...

Is your phone a calling companion or callout snitch? The Electronic Frontier Foundation delivered findings about some Android phones on Thursday—concerning newer, not older, models. According to EFF findings, a number of ...

Recommended for you

It sounds like a science-fiction nightmare. But "killer robots" have the likes of British scientist Stephen Hawking and Apple co-founder Steve Wozniak fretting, and warning they could fuel ethnic cleansing and an arms race.

A startup team calls their work a product. They also call it a social movement. Many people in the over-7,000 islands in the Philippines lack access to electricity .The startup would like to make a difference. Their main ...

Are some people fed up with remembering and using passwords and PINs to make it though the day? Those who have had enough would prefer to do without them. For mobile tasks that involve banking, though, it is obvious that ...